At top speed gunsmith and USA title holder Mitchell Maxberry said it took him seven seconds to reload a shotgun similar to the one featured in the Scott Guy murder trial.

Ewen Macdonald is charged with murdering Guy, his brother-in-law, on July 8, 2010 at 4.43am. He is on trial in the High Court at Wellington.

The Crown says he killed Guy by shooting him in the throat with the farm's shotgun over tensions about the future of the family farm in Feilding.

This morning the court heard Guy was shot twice. He was fatally shot in the neck and then shot again as he was falling or lying on the ground. That shot caused damage to his arm. The Crown has finished presenting evidence to the jury.

This afternoon, defence lawyer Greg King began his opening address by telling jurors he was calling two witnesses and Macdonald would not be one of them. The defence has since finished presenting its evidence.

The jury heard that at top speed gunsmith and USA title holder Mitchell Maxberry took him seven seconds to reload a shotgun similar to the one featured in the trial.

Maxberry told the jury he had won five national titles, some long range and rapid fire competitions and had owned hundreds of guns.

He said before the trial he test fired to see how far a wad would be shot from a gun and how fast three shots could be fired from a similar gun to the shotgun on the Guy family farm.

He said the cartridges had to be physically pulled from the gun rather than ejected automatically when the gun was opened.

Maxberry said he put two rounds in the gun and could be fired in about a second. He said each cartridge then had to be removed and another put in and that took about seven seconds.

He said he was doing it as fast as he could and used the Winchester bushman ammunition similar to what was part of the trial.

Crown prosecutor Ben Vanderkolk asked if he was being timed while he was shooting. Maxberry said he was timed by a stopwatch.

He said it was usual to remove both cartridges at once because only removing one could cause a jam.

King called an electrical engineer as his first witness, who told the jury that transmission lines would not affect how a digital clock worked.

Early in the trial Guy's neighbour Derek Sharp was unable to be precise about when he heard shotgun blasts because his clock was not accurate.

He had said he had always thought that the clock gained time because he lived under transmission lines.

Engineer Peter Shelton took readings under the power lines.

He said there would be no effect whatsoever on a reading on a digital clock. Shelton admitted to Crown prosecutor Paul Murray he had never seen Sharp's digital clock.

At the end of the defence evidence, Justice Simon France told the jury they would hear closing addresses from both sides.

He asked the jury to think about if they wanted to begin deliberating on Friday or return next week to begin. They are to consider it overnight.

ACCUSED 'TOLD THE TRUTH'

In his opening address, King said Macdonald had told the truth in police interviews about what happened the day Scott Guy was killed.

He admitted that "to his eternal shame" Macdonald had not told the truth about events like the arson of the old house and vandalism of Scott and Kylee Guy's new home.

King said, however, during 40 hours of police interviews Macdonald was truthful about what happened to Guy.

Just because Macdonald pleaded guilty to other charges of arson and criminal damage did not mean he was guilty of murder, King told the jury.

He said it was not enough to think that Macdonald might have miraculously worn dive boots too big for him, or rescued his own from a fire two years ago. The Crown says the accused wore a pair of Proline dive boots when he allegedly shot guy. Dive boot prints were found at the murder scene.

Macdonald, he said, did not have to help the police, take them on tours of the farm or give them DNA, or speak to them all the while carrying the dark secret of his past actions toward Guy.

"They are despicable and he will be punished for them,'' he said.

He added there was an absolute abundance of doubt in the case.

KILLED BY FIRST SHOTGUN BLAST

Forensic scientist Kevan Walsh said he examined a cap worn by Scott Guy and found near his body.

The fatal blow struck him under the chin and caused a 6cm wound to his carotid artery.

Walsh said the second shot appeared to be made as Guy was falling or on the ground.

The damage to the underside of the peak of the cap showed the direction of the shotgun pellets going up. The pellets from the second shot had struck Guy's face.

"He may have been falling backward ... his left arm raised, up near the cap, so some of the pellets hit the forearm and thumb and some the cap," Walsh said.

Walsh said he and Dr John Rutherford, who performed the autopsy, had talked about whether there were one or two shots.

Walsh said the shot which hit the underside of Guy's chin was from the left.

There were some single pellet holes to the chin, caused by individual pellets.

He said in his opinion the wound was created by one shot.

Walsh told the jury he found a second wad from a shotgun near where Guy's ute had been discovered running.

Walsh began searching the scene after attending Guy's autopsy. He said he looked at fence palings and found pellet strikes in the right side of the fence.

"Upon removing the tent that was covering the vehicle I found a wad on the ground near to the fence," he said.

A shotgun wad was also found in Guy's neck during the autopsy.

Walsh said one of the shots was fired from the right of the nearby fence. The second shot fired at Guy came from the fence line just outside the gate, the jury was told.

Walsh said he examined the scene to determine the likely position of the shooter and the firing distance.

He said he could not tell the height the shot was fired from as he did not have enough precise information. Walsh estimated the shots were likely fired close to the fence or just a few feet away from it.

He said he had no information that told him the position of the shooter during the shot that killed Guy.

He told the jury that most of the pellets from the second shot went over Guy, likely because he was falling backwards at the time.

GUY 'COULD NOT HAVE GRABBED GUN'

Walsh said he test fired shotguns, including side-by-side barrelled guns and under-and-over barrels.

He told the jury the further away the shot was fired from, the greater the spread of the pellets.

He examined the spread and distribution of the pellets within that spread in comparison with the wound Guy had to his neck.

Walsh said a double-barrelled under-and-over shotgun would need to have been fired from 2-4 metres away.

The wads found in Guy's neck and on the ground near the car pointed toward the ammunition being made by Winchester in Australia.

Walsh said the weight of the pellets was between 32 and 36 grams; mostly likely Winchester bushman brand no 5 shot.

He used that shot to do the testing.

The Crown has told the jury that the same type of ammunition was found on the farm.

Walsh said he also test fired the Guy family farm shotgun, an under-and-over barrelled shotgun.

He said the distance for the firing of the top barrel would, in his opinion, would be about 3.5m to 4.5m away and the firing of the bottom barrel would be no closer than 2m.

Walsh said Guy would not have been able to reach the shotgun.

AMMO HAD SAME TYPE OF WADDING

Ammunition taken from Macdonald had the same type of lead shot and wadding as found near Guy's body.

Walsh examined shot and wadding given to police by Macdonald. He also examined cartridges.

He told Crown prosecutor Ben Vanderkolk he could not exclude that the farm shotgun was used to shoot Guy but there was no direct link to that gun.

"It's simply the fact it's a 12-gauge shotgun and 12-gauge wads were recovered that I can't exclude it but I could not exclude any other shotgun.''

Wadding taken from Guy's father Bryan's ammunition was the same type as found at the scene on Aorangi Rd.

Walsh also examined a series of wads from a variety of people - all others had a different type of wadding, He said he was also asked to consider if Guy could have been shot from the roadway and he said he did not think it was possible.

FARM GUN WAS OPERATIONAL

Police armourer Robert Ngamoki examined the farm's shotgun.

He conducted tests on the trigger designed to see if the gun worked as it was supposed to.

He tested the pressure needed on the trigger to fire the gun. It was 2.5kgs.

Ngamoki said he test fired the gun to determine if it worked.

Cartridges were not automatically ejected from the gun, but were raised slightly to allow them to be removed by hand.

Defence lawyer Greg King asked if he tested to see if the cartridges would fall out if he turned the gun upside down, but Ngamoki said he had not.

The gun was not tested until this year, 18 months after the Crown say it could have been the weapon used to shoot Guy.

UNABLE TO TRACE MURDER WEAPON

Earlier, Walsh explained to the jury how a cartridge was made up and how a gun worked.

He said in a rifle or a pistol there were grooves in the barrel. A bullet was marked by the grooves as it travelled down the barrel, making it possible to compare test-fired bullets.

However, a shotgun had a smooth barrel and Walsh said there was no way the lead pellets used in a cartridge received any marks as they were fired down it.

He told the jury it was not possible to determine if pellets came from a particular shotgun.

* Correction: Witness Peter Shelton was originally referred to as Peter Schouten in this article. We apologise for the error.